In a conventional processing machine such as a lathe, a processing target (hereinafter, referred to as a workpiece) is fixed to a main spindle, and a part of the workpiece projecting from the leading end of the main spindle is processed by a tool while rotating the workpiece by rotating the main spindle about an axis. Some processing machines include a guide bush which supports a workpiece just proximal to a processing tool between a leading end of a main spindle and the processing tool. Such a guide bush is attached to a guide bush-supporting base fixed ahead of the leading end of the main spindle, and the workpiece is supported to be rotatable about an axis and movable in an axis direction.
It may be desired to perform processing without using a guide bush depending on a processing type and/or a condition of a workpiece even though the processing machine includes the guide bush.
A processing machine is therefore proposed in which a guide bush is removed from a guide bush-supporting base according to a condition to enable processing without using the guide bush (Patent Literature 1).
In this processing machine, a guide bush attachment hole for attaching a guide bush is formed in a guide bush-supporting base formed to be orthogonal to an axis direction of a main spindle, and the main spindle supporting the workpiece moves forward to the guide bush attachment hole to process the workpiece in a state in which the guide bush is removed from the guide bush-supporting base.